Disclosure & Reasonable Accommodation
The extent to which early onset Parkinson's disease presents challenges at work may depend on who in your organization you decide to tell about your diagnosis, when and how.
There are many guidelines when it comes to decisions about disclosure and requests for reasonable accommodation but no clear "rules." Managing these decisions in a way that balances what is best for you and what is best for your employer is ideal to maintaining your employment.
The variability in symptoms and progression from one person to another makes it impossible to predict when changes in your employment situation might become necessary. The "not knowing" can make life in general feel out of control and sometimes lead people to rush into a decision prematurely. Instead, allow yourself to slow down and really think. Research the benefits available to you now and in the future, either through your employer or privately, and begin doing some parallel or contingency planning. In other words, you may want to (and plan to) be working five or ten years from now. Just be willing to entertain one or two alternate plans should that expectation at any point become unrealistic.